1. Field of the Invention
This invention relates to the removal of particulate fines from the return run of a continuous conveyor and, more specifically, to the removal of animal food fines that fall through the load run and accumulate on the return run of a substantially horzontal, foraminous, endless, cooler conveyor that is fed by a pellet mill or the like. In particular, the invention relates to a food pellet fines removal system in which, in the operation of a substantially horizontal cooler/dryer, the fines are collected on the return run, conveyed on the load run to the discharge end of the conveyor and, thence, passed through the conveyor at its discharge end for ultimate removal with the food product.
2. Description of the Prior Art
Applicants' assignee manufactures a horizontal pellet cooler that generally consists of one or more chain and sprocket driven perforated metal carriers enclosed in a housing. Each carrier is made up of individual trays joined together to form an endless belt having an upper surface (the product or load carrying side) and a lower surface (the return side). Hot, moist, pellets are distributed on the upper surface and they are cooled and dried as air is drawn through the carrier perforations. The diameter of the perforations is selected to be smaller than the nominal size of the pellets being conveyed. However, a portion of this material, i.e., fines, will be small enough to pass through these perforations.
In general, if these fines are able to pass through the upper surface, they should be able to pass through the lower surface. However, this is not always the case. A portion of these fines will be retained on the lower surface and will be carried toward the turn-around end. This material becomes trapped and, in time, a sufficient quantity of fines can accumulate to cause problems. One of these problems is possible contamination of subsequent material processed through the cooler. Another problem is that a sufficient quantity of fines can accumulate and cause individual trays to bow or bend under this load. These trays have been designed to be loaded on the upper surface only. In any other position they are weak and will gap or will separate.
One known solution for the removal of these trapped fines is the use of screw flighting mounted on the sprocket shaft of the carrier. This flighting is welded to the shaft and is so arranged to deflect the fines toward the outside edges of the carrier. Slots are cut in the sprockets for passage of the fines material therethrough. This method, while partially successful, does have several drawbacks. First, a sufficient quantity of fines must accumulate before the flighting can be effective. Second, once the material is moved outside the carrier, there is still a problem with its removal from the carrier housing. Also, there are ledges where it can accumulate as it attempts to fall to the bottom of the carrier housing. Accordingly, a better fines removal system has been sought.
Additional known conveyor cleaner systems are those disclosed in U.S. Pat. No. 3,504,786 to Matson and U.S. Pat. No. 3,759,369 to Vering et al. However, neither of these conveyor cleaner systems are found to be pertinent to the fines removal system of the present invention.